Light producing ignitible composition



Patented Sept. 5, 193g PRODUCING IGNITIBLE COMPOSITION 7 Stanley. HectorLucas, Witton, Birmingham, V England, assignor to Imperialv Chemicallindnstries Limited, a corporation of Great Britain No Drawing.Application July 7, 1932, Serial No,

LIGHT 621,314, and in 1931 This invention relates to improvementsin compositions which when ignited emit albrilliant light and which consist ofa metallic powder mixed with an oxidizing agent. such'compositionsconsist essentially of one or morefinely divided metals such asmagnesium, aluminium and zirconium, and oxidizing agents'such aspotassium chlorate, barium nitrate, potassium nitrate,

, barium. peroxide and the like. These light producing ignitible powdersfind application in the art of pyrotechny, as flash powders forphotographic purposes, and they are also applied for obtaining tracingeffects in military and other,

forms of ammunition. The compositions hitherto used have had certaindisadvantages, such as the sensitivity to shock or friction associatedwith those containing potassium chlorate as the oxidizing agent. Otherscontaining barium peroxideas the oxidizing agent are unstable and sufferdeterioration. when exposed to the atmosphere.

Those containing nitratesare diflicult to ignite,

and further, barium salts are toxic and therefore undesirable undercertain conditions of use, e. g.v connection with tracer pellets forvshot gun:

5" cartridges.

The objects of this invention are to produce an improved light emittingignitible composition which is not sensitive to ignition by shock or;

51 j friction, which is stable whenexposed to the at'-. mo'sphere, whichis easily ignitible and non toxic. I have found thatthese objects areobtained if the oxidizing agent used in combination with the metallicpowder is bismuth oxide or sodium bismuthate or mixtures of these twocompounds.

'35 Sodium bismuthate is. an oxidizing agent and details of itspreparation and properties are given 7 in volume 9 of MellorsComprehensive Treatise on Inorganic and Theoretical Chemistry. I Bismuthoxide is preferable, to sodium bismuthate since experience has shownthat the compositions containing sodium bismuthate,- although stable inordinary atmospheres, are apt to be aiTected by excess of moisture orexposure to a humid atmosphere for long periods. It appears that underthese conditions the sodium bismuthate reacts with the metallic powder,e. g. magnesium, and the ignitibilityof the composition is therebyimpaired. Bismuth oxide, how- 5 ever, does not behave in this way.

" It has'also been found that the metallic pow- Great Britain October21,

7 Claims. (01. 52 24) I ders themselves tend to deteriorate when exposedto moisture for long periods and that it is therefore desirable, inorder to obtain an absolutely reliable product, topack the same'inair-tight containers. Accordingly, in the manuiacture'of tracer pelletsfor ammunition, the composition Jmay be pressed into moisture-proofcapsules, the

open ends of which are sealed by means of metal foil so that the pelletsarecompletely' air and moisture tight.

As an example of one improved light emitting composition prepared inaccordance with the invention, I may mention a mixture of two parts ofmagnesium powder and three parts of bismuth oxide, which when pressedunder a load of ten cwts. into tracer pellets for shot guncartridgesgives excellent results, having the desired properties ofcertainty of ignition, brightness of trace, and freedom from danger ofpossible toxic efieots. Similar resultsare obtained with a mixture ofone part magnesium powder and one to two parts of sodium bismuthate.

As a 'further example Ifmay mention a composition containing three partsof bismuth oxide,

. two parts of magnesium powder or other suitable metallic powder, andhalf a part of strontium v peroxide. -The addition of the strontiumperoxide changes the'white colour of the flame emitted :by the tracingcomposition'to a reddish, colour and in brilliant sunlight thetrace ismuch more 'disce'rnible than a completely whitelight.

While I have referred principally to the use of the improvedcompositions in connection with tracer pellets for shot gun cartridges,it is to be understood that they are also applicable for a Variety ofother purposes such as those mentioned 4. A light-emitting ignitiblecomposition comprising magnesium powder and bismuth oxide.

5. A light-emitting ignitible composition comprising magnesium powderand sodium bismu- I thate. V

1 6. A light emitting ignitible composition consisting of two parts byweight of magnesium powder and three parts of bismuth oxide.

7. A light-emitting ignitible composition consisting of one part byweight of magnesium powder and 1-2 parts of sodium bismuthate.

v STANLEY HECTOR,'LUCAS.

